This invention relates generally to electric lamps and particularly to discharge lamps for use on motor vehicles, among other applications. More particularly, the invention pertains to a discharge lamp system featuring cableless connection between a discharge lamp assembly and a lighting circuit assembly.
Discharge lamps, notably including metallic halide lamps, are finding use as light sources of vehicular headlamps. There has, however, been a problem left unsolved in the use of discharge lamps for vehicular headlamp applications.
The discharge lamp needs an electric lighting circuit for providing a high voltage required for an electric discharge to take place between the pair of electrodes of the lamp unit. Cables or cords have so far been used for electrically connecting the discharge lamp to the lighting circuit. The present applicant objects to the cable connection, particularly in use of discharge lamps on motor vehicles. One reason for this objection is the possibility of current leakage from the cables, as the motor vehicle has many electrically conducting parts. Another reason is that the cables are prone to produce electric noise. Such sources of noise production should be eliminated as today's vehicles, passenger cars in particular, are furnished with an increasing number of electric or electronic appliances.
For all these reasons there have been strong demands from the automobile industry for the advent of cableless discharge lamps.